No. Really, no.
There is no good reason for any website to be serving a mobile-specific site in 2018. In fact, the idea of a “mobile” site shouldn’t even exist anymore—every site should be a mobile site.
With responsive web design and progressive enhancement, in particular, the requirement for a mobile-specific site has long disappeared. Besides it simply not being standard practice anymore, separate sites for mobile devices actually hinder your site’s offerings on a multitude of levels.
Websites still using mobile sites do so because of the fear of cross-compatibility on older devices, and usually for a service which is integral for users to have access to on a mobile device as well as a desktop computer. Banks for instance. However, while in these use cases there is a good rationale, responsive design with progressive enhancement is more than capable of managing this problem.
There is a misjudged belief by some web developers that websites of a certain caliber are “safer” to serve with a mobile-specific design, in the sense that they will work more reliably on smaller, older mobile devices.
In fact, this is far from the truth. Responsive design, coupled with progressive enhancement, results in clean, cross-platform websites which are suited to any device.
The only acceptable (or necessary) use case for mobile-specific sites today, would be in the event that the site serves content or features which are drastically different than the desktop version of the website.
If the content is the same, however, it makes far more sense to build a responsive website that utilizes the technology of progressive enhancement.
For some great examples of designs which utilize responsive design and progressive enhancement in tandem, check out our Drupal themes or Joomla templates.
If you need the help of web development specialists to incorporate progressive enhancement into your current website, take a look here.